The present invention relates to an arrangement for sealingly mounting rotary members on supports in general, and more particularly to an arrangement for sealingly mounting a propeller shaft in a passage provided in a hull of a watercraft, such as a motorboat or yacht.
It can be observed that streams or bodies of water suffer of an ever-increasing pollution, especially when they are navigable and carry a substantial amount of boat traffic. A frequent source of this pollution is to be found in imperfect sealing of the driving elements which lets grease, oil or other lubricants escape into the water. One, and possibly the most offending, location at which this escape of lubricants may occur is the region of the support sleeve which passes through the stern zone of the hull of the watercraft and through which the propeller shaft extends from the interior to the exterior of the hull. Experience has shown that the worst offenders in this respect are small motorboats and yachts. This is primarily attributable to the fact that conventional bearings which are used in such watercraft are subjected to substantial loads and must be continuously lubricated. The bearing seals are subjected to a high degree of wear, so that the lubricants can escape and reach the water via the support sleeve which passes through the stern of the watercraft. On the other hand, water can also penetrate into the propeller shaft bearing which is accommodated in the interior of the support sleeve, so that corrosion phenomena can soon be observed at this region. A further disadvantage of the conventional propeller shaft mounting arrangements is to be seen in the fact that their assembly or mounting and disassembly or dismounting are not easy, especially since, in most instances, the propeller shaft has different diameters at different regions within the support sleeve. Even a small deviation from parallelism among the shaft, the support sleeve, and the prime mover, which can easily come in existence as a result of non-uniform transversely acting forces, often results in damage to the propeller shaft.